Engine test cell

ABSTRACT

An engine testing system comprises a rotary absorber that provides a variable resistance to an engine under test and heats coolant from a cold reservoir. A hot reservoir coupled to rotary absorber stores the heated coolant for later (or concurrent) use. Moreover, an organic Rankine cycle turbine-generator device is coupled to the hot reservoir, which converts heat from heated coolant into electrical power. A conditioning system is coupled to the organic Rankine cycle turbine-generator device that cools the coolant for storage in the cold reservoir. The available captured waste energy may be augmented with waste energy that is also available during engine testing. The additional waste energy may be in the form of exhaust gases, thrust, heat from engine coolant systems, residual engine heat, radiant or convective waste heat, friction etc. Variations of the above system may replace the primary energy re-capture from other than a rotary absorber.

BACKGROUND

Various aspects of the present disclosure relate generally to enginetesting and more particularly to test facilities for testing engines,which capture waste energy from engine testing operations and transformthe captured waste energy into usable energy.

When testing an engine, a load on a shaft of the engine may be simulatedthrough the use of a loading device such as a rotary absorber,electrical generator, pump, or dynamometer. As an illustrative example,a rotary absorber is coupled to the shaft of the engine to supply avariable resistance (i.e., reactionary torque) to the shaft as theengine is operated. The amount of resistance supplied by the rotaryabsorber is controlled as part of the test operation to simulate theload. As the shaft of the engine turns, power transmitted through theshaft is (ultimately) converted to heat through the application of thisresistance.

The manner in which the generated heat is removed from the testingsystem depends largely on the type of loading device. For instance, inmany forms of mechanical rotary absorbers, a coolant carries heat energyaway from the rotary absorber. The heated coolant is pumped to anevaporative cooler or some other heat exchanger device, where it iscooled. On the other hand, an electrical rotary absorber, such as aneddy current brake typically requires cooling for the generatorwindings, which is usually accomplished by liquid heat exchange. Asanother example, an air dynamometer dissipates heat directly to theatmosphere. As yet another example, an electrical generator ordynamometer produces electricity from shaft rotational energy that isrouted to resistor banks.

BRIEF SUMMARY

According to aspects of the present disclosure, an engine testing systemfor testing engines (e.g., internal combustion shaft engines) comprisesa cold reservoir, a rotary absorber, a hot reservoir, an Organic RankineCycle (ORC) turbine-generator device, and a conditioning system. Theengine testing system also comprises a primary coolant loop arranged toenable coolant to flow from the cold reservoir to the rotary absorber,from the rotary absorber to the hot reservoir, from the hot reservoir tothe ORC turbine-generator device, from the ORC turbine-generator deviceto the conditioning system, and from the conditioning system back to thecold reservoir.

In operation, the rotary absorber provides a variable resistance torotation of a shaft of an engine under test during an intermittentengine testing operation, producing waste energy. Cool coolant (e.g.,water, oil, or other form of heat transfer fluid) from the coldreservoir carries away the waste energy from the rotary absorber asheated coolant, which is provided to the hot reservoir via the primarycoolant loop. The heated coolant from the hot reservoir is provided tothe ORC turbine-generator device via the primary coolant loop. Here, theORC turbine-generator device converts heat from heated coolant intoelectrical power. Moreover, the conditioning system conditions coolantfrom the ORC turbine-generator device for storage back in the coldreservoir, also via the primary coolant loop.

According to further aspects of the present disclosure, an enginetesting system for testing engines comprises a first energy conversiondevice that converts waste energy derived from intermittent enginetesting operations into heat that heats a coolant. The engine testingsystem also comprises a second energy conversion device that convertswaste energy derived from intermittent engine testing operations intousable energy, where the second energy conversion device operatesindependently of the first energy conversion device. The engine testingsystem also comprises a hot reservoir that stores the coolant heated asa result of the intermittent engine testing operations. Still further,the engine testing system comprises an electrical power generatingdevice coupled to the hot reservoir, which converts heat extracted fromthe coolant stored in the hot reservoir into on-demand electrical power.The engine testing system yet further comprises a primary coolant loopthat couples the coolant from the hot reservoir to the electrical powergenerating device.

According to yet further aspects of the present disclosure, an enginetesting system comprises an electric generating device (e.g., aturbine-generator or a dynomometer) that coverts intermittent wasteenergy of an engine under test into electrical power. The engine testingsystem also comprises a hot reservoir, an Organic Rankine Cycle (ORC)turbine-generator device, and a primary coolant loop arranged such thatheated coolant flows from the hot reservoir to the ORC turbine-generatordevice, which converts heat from heated coolant into electrical power.The engine testing system further comprises a resistive load coupled tothe electric generating device that converts electrical energy from theelectric generating device into heat that is utilized to heat thecoolant.

According to further aspects of the present disclosure, the resistiveload may be implemented as a heating element that heats the coolant inthe hot reservoir. Alternatively, the resistive load may be coupled to aheat exchanger that transfers heat from the resistive load to a heatedworking fluid. Here, a second loop transfers the heated working fluid tothe ORC turbine-generator device.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a block diagram of an engine testing system, according tovarious aspects of the present disclosure;

FIG. 2 is a block diagram illustrating an Organic Rankine Cycle (ORC)turbine-generator device, according to various aspects of the presentdisclosure;

FIG. 3 is a block diagram illustrating of an engine testing systemhaving supplemental cogeneration systems, according to various aspectsof the present disclosure;

FIG. 4 is a block diagram illustrating another engine testing systemhaving supplemental cogeneration systems, according to various aspectsof the present disclosure;

FIG. 5 is a block diagram illustrating yet another engine testing systemhaving supplemental cogeneration systems, according to various aspectsof the present disclosure;

FIG. 6 is a block diagram illustrating yet another engine testing systemusing an electric generating device coupled to an engine under test,according to various aspects of the present disclosure;

FIG. 7 is a flow chart illustrating a method for testing engines andusing heat generated from the testing of the engine for cogeneration ofelectrical power, according to various aspects of the presentdisclosure;

FIG. 8 is a flow chart illustrating another method for testing enginesand using heat generated from the testing of the engine for cogenerationof electrical power, according to various aspects of the presentdisclosure; and

FIG. 9 is a flow chart illustrating yet another method for testingengines and using heat generated from the testing of the engine forcogeneration of electrical power, according to various aspects of thepresent disclosure.

DETAILED DESCRIPTION

According to aspects of the present disclosure, systems are provided forthe testing of engines, such as conventional driven-shaft internalcombustion engines, turbo-shaft jet engines, gas turbine engines, andthrust engines. In such engine testing systems, waste energy fromintermittent engine testing operations is effectively captured andoptionally stored. The collected waste energy is converted to usefulenergy, e.g., electrical power, upon demand over an extended period oftime. For instance, electrical energy may be generated on the order ofhours or even days after the testing operations have been performed andthe waste energy collected.

When conducting tests on typical shaft engines, waste energy (e.g.,relatively high power but low grade waste energy) is generated in theform of heat. According to certain embodiments described more fullyherein, a coolant carries this heat away from the engine under test to astorage reservoir, referred to herein as a hot reservoir. The heatstored in the hot reservoir is converted to useful energy, e.g.,electricity, on-demand by coupling the heated coolant from the hotreservoir to a turbine-generator device, such as an Organic RankineCycle (ORC) turbine-generator device, which converts heat toelectricity. The coolant exiting the turbine-generator device can thenbe recycled to perform additional engine testing operations.

Intermittent engine testing operations may also generate other forms ofwaste energy. For instance, an engine testing operation may generateadditional waste energy in the form of exhaust gases, thrust, heat fromengine coolant systems, residual engine heat, radiant or convectivewaste heat, friction etc. As will be described in greater detail herein,in certain embodiments, this additional waste energy is captured as analternative to, or for use in combination with, the collection of theabove-described shaft waste energy. This other waste energy may becaptured by heating a working fluid, by converting the waste energydirectly into usable electrical power (e.g., using a turbine-generator),by extracting heated coolant from the engine under test, by combinationsof the above, etc.

The electrical power generated by the engine testing system may be usedto power various components of the engine testing system itself, such aspumps, conditioning systems, control units, heating elements, etc.Electrical power generated by the engine testing system may be used topower other devices not related to the engine testing system that arewithin the engine testing facility. Still further, electrical powergenerated by the engine testing system may be tied into a main powergrid.

In this regard, electrical power generated by the engine testing systemcan be kept independent and isolated from power on the main power grid.Alternatively, power generated by the engine testing system may beprovided to devices that share an electrical connection to the mainpower grid.

System Overview:

Referring to drawings and in particular FIG. 1, an engine testing system100 is implemented as a test cell, as is shown in block diagram form. Anengine 102 under test includes an output shaft 104 that couples to aloading device. Example engines 102 may comprise reciprocating pistonengines, rotary or Wankle engines, gas turbine engines, turbo-shaft jetengines, turbo-prop jet engines, etc.

Primary Waste Energy Capture:

In certain embodiments, the loading device is a rotary absorber 106. Ingeneral, the rotary absorber 106 is a device that loads the engine 102during testing and converts mechanical energy to heat energy, electricalenergy, kinetic energy, or a combination of all three. For instance, theoutput shaft 104 of the engine 102 under test may directly drive therotary absorber 106. Moreover, in some embodiments the output shaft 104couples to the rotary absorber 106 through an optional intermediatedevice, such as a gearbox 108, a flywheel 110 (inertia wheel), or both.For instance, a gearbox 108 may be useful to match the engine outputspeed to the operational speed range for the rotary absorber 106. Aflywheel 110 (inertia wheel) may be used to simulate the inertia of adevice that the engine 102 was designed to power.

The rotary absorber 106 acts as an energy conversion device byconverting waste energy derived from intermittent engine testingoperations (shaft power) to heat that is carried away by a coolant(e.g., water, oil, or other form of heat transfer fluid). In certainembodiments, the rotary absorber 106 is implemented as a hydraulicbrake. The hydraulic brake is referred to as a water brake when thecoolant is water. In other embodiments, the rotary absorber 106 isimplemented as an eddy current brake, friction brake, or other suitableabsorber technology.

In some embodiments, the loading device is implemented as an electricalgenerator or dynamometer that is coupled to the engine shaft thusconverting rotational energy to electricity that is then routed to aresistor bank or other electrical load device where the electricalenergy is converted to heat. The resistor bank or electrical load devicemay be air or liquid cooled. Thus, the electrical generator ordynamometer, when configured as above with the load device being liquidcooled, can be considered an indirect form of liquid cooled rotaryabsorber 106. The particular type of rotary absorber 106 will likelyvary depending upon the loading requirements of the engine under test.

As illustrated, a cool-coolant pump 112 is utilized to supply coolcoolant from an outlet 114 of a cold reservoir 116 to the rotaryabsorber 106. In some embodiments, a control unit 118 is connected to,and controls the cool-coolant pump 112 to regulate the amount of coolantsupplied to a coolant inlet 120 of the rotary absorber 106. Heatedcoolant exits the rotary absorber 106 via a coolant outlet 122, and isdelivered via an optional heated-coolant pump 124 to a hot reservoirinlet 126 of a hot reservoir 128. In some embodiments, theheated-coolant pump 124 is controlled by the control unit 118 or by someother control unit (not shown). In this manner, a first section of aprimary coolant loop 130 is utilized to transfer cool coolant from thecold reservoir 116 to the rotary absorber 106, and to transfer coolantheated by the rotary absorber 106 to the hot reservoir 128 duringintermittent engine testing operations. The primary coolant loop 130will be described in greater detail herein.

In practical implementations, the rotary absorber 106 can be implementedas a direct mounted rotary absorber 106 that is mounted directly to theengine 102 under test. Alternatively, the rotary absorber 106 can beimplemented as part of a stationary driveline consisting of apermanently mounted rotary absorber 106 with optional flywheel, gearbox,etc. A direct mounted rotary absorber 106, e.g., engine mounted waterbrake, has certain advantages, in that the direct mounted rotaryabsorber 106 is much smaller and ligher than other forms of rotaryabsorbers 106, thus facilitating greater test cell availability.

In an illustrative implementation, the rotary absorber 106 may beprepped to an engine 102 outside of the test cell while another engine102 is being tested in the test cell, thus increasing test cellavailability. The ability to prep an engine 102 to a rotary absorber 106is facilitated because the direct mounted rotary absorber 106 may bedirectly mounted to the output shaft 104 of the engine 102 under test.Yet further, the direct mounted rotary absorber 106 requires nocomplicated high-speed drivelines inside the test cell, thusfacilitating modularity.

Moreover, fixtures to hold engines during tests are less complex thancomparable fixtures used in connection with larger stationary electricaldynamometers or water brakes, facilitating easier loading, reducedmaintenance and simpler calibration procedures. However, because thedirect mounted rotary absorber 106 may have a low polar mass moment ofinertia, it may be necessary to use analog or digital control methods tosimulate inertia loading by commanding additional torque so that theengine 102 under test is subjected to desired loading when beingaccelerated or decelerated during a test procedure.

As shown in FIG. 1, there is only one cold reservoir 116. However, theremay be any number of cold reservoirs 116 storing cool coolant for use byone or several rotary absorbers 106 located in multiple test cells.Similarly, in practice the hot reservoir 128 may be implemented as oneor more hot reservoirs 128. Moreover, the hot reservoir 128 may beinsulated or otherwise fabricated to retain the heat of the coolantstored therein. Further, the hot reservoir 128 may be elevated toincrease potential energy of the coolant (e.g., to create headpressure), which may be recoverable at later times.

The sizes of the cold reservoir(s) 116 and the hot reservoir(s) 128 aredetermined based upon the engine testing needs. Generally however,testing can produce hot coolant that will remain at an elevatedtemperature sufficient to operate an ORC turbine-generator device(described later) for a period of time, e.g., several hours or longer,depending at least in part upon the temperature of the coolant and theamount of coolant stored in the hot reservoir 128.

The heated coolant remains in the hot reservoir 128 to preserve the heatuntil needed for use. When the heated coolant is needed (e.g., during orafter testing), a heated-fluid bleed pump 132 bleeds the heated coolantthrough an outlet 134 of the hot reservoir 128 to feed an energyconversion device, e.g., an ORC turbine-generator device 136. Moreparticularly, heated coolant enters the ORC turbine-generator device 136through a fluid inlet 138 and exits the ORC turbine-generator device 136via an outlet 140.

As explained in greater detail below, the ORC turbine-generator device136 converts heat from the heated coolant from the hot reservoir 128into electrical power. Power generated by the ORC turbine-generatordevice 136 can be used, for example, to power one or more components ofFIG. 1 that draw power. Any component of the engine testing system 100that may receive electrical power from the ORC turbine-generator device136 may also be configured to receive power from an alternate source(e.g., an alternating-current feed from a facility power grid). Thus,when the ORC turbine-generator device 136 cannot supply enough power tothe component, the component may draw power from the alternate powersource. For instance, such may be the case during system start-up whenpower is needed to create flow prior to the ORC turbine-generator device136 generating power.

As the ORC turbine-generator device 136 converts the heat from theheated coolant into electrical power, the heated coolant cools somewhat.Thus, the coolant that leaves the ORC turbine-generator device 136 is ata reduced temperature compared to the coolant that enters the ORCturbine-generator device 136. However, the coolant is likely not at asuitably cooled temperature for proper or efficient operation of manytypes of rotary absorbers 106. By way of example, in an embodiment usinga water brake for the rotary absorber 106, the water coolant provided bythe cold reservoir 116 must be less than 50 or 60 degrees Celsius inorder to have effective heat transfer.

As such, the coolant may be further cooled before being returned to thecold reservoir 116 to be recycled to the rotary absorber 106 forsubsequent testing. As such, the coolant passes to an inlet 142 of anoptional conditioning system 144 that further conditions the coolant.For instance, after exiting the ORC turbine-generator device 136, thecoolant may be lukewarm and unsuitable for optimal operation of therotary absorber 106. Thus, for example, the conditioning system 144 mayfurther cool the coolant (e.g., through a secondary heat exchanger) tocreate cool coolant for storage back in the cold reservoir 116.

The conditioning system 144 may also monitor and adjust the coolant foroptimal system performance. Notably, the “quality” of the coolant canhave a profound impact on the longevity of the rotary absorber 106 fromwear, corrosion, and other aspects. Many times, longevity can beincreased by removing impurities, maintaining a desired pH (acidity)level, physical chemistry (shear characteristics), and by injectingsmall amounts of additives that inhibit corrosion and help lubricate theinternal components of the rotary absorber 106 that may come in contactwith the coolant such as rotors, shafts, bearings and seals. Thus in anexample embodiment, the conditioning system 144 treats the coolant to:further cool the coolant, maintain a proper pH level of the coolant,maintain a proper lubricity of the coolant for use in the rotaryabsorber 106, remove any impurities that may be introduced into thecoolant during the testing, provide deionization of coolant water, addlubricating agents, or combinations thereof. The monitoring andadjustments performed by the conditioning system 144 can be automatedvia control by the control unit 118, or via another suitable controldevice.

A cool-coolant fill pump 148 pumps the cool coolant from an outlet 146of the conditioning system 144 to fill the cold reservoir 116 through aninlet 150 of the cold reservoir 116. Thus the engine testing system 100is a closed system in regard to the coolant. The closed system isdefined by the primary coolant loop 130, which provides a coolantpassageway from the cold reservoir 116, through the rotary absorber 106,to the hot reservoir 128, through the ORC turbine-generator device 136,through the conditioning system 144, and back to the cold reservoir 116.

In an illustrative example, engine testing operations may be carried outintermittently throughout a day (e.g., intermittently on first andsecond shifts) at a facility based on testing requirements for thatspecific day while generating electrical power to meet instantaneousrequirements of the facility. The heated coolant is thus collected andbled off as needed to the ORC turbine-generator device 136 to meet thepower requirements (e.g., pumping, cooling, lighting, controls, etc.,combinations thereof) of the engine testing system 100, other collocatedengine testing systems at the testing facility, other devices at afacility, etc. For instance, in testing an example turbo-shaft jetengine, 10 to 25 kW or more of on-demand electricity may be generatedcontinuously over a 24 hour period from a single test that was performedduring a 3 hour period during the previous day. Higher levels ofon-demand electricity can be generated for smaller periods of time.These levels of power can be readily absorbed by most test facilitiesover an extended time period without requiring surplus energy to be fedback to the main utility grid. Therefore, energy savings (i.e., thepower generated from the waste heat recovered from engine testingoperations) can be realized at the facility without having to complywith any restrictions imposed by local electrical utility authoritiesbecause none of the electrical power generated by the ORCturbine-generator device 136 needs to be fed back to the main powergrid.

In an example implementation, to meet (or at least offset) theinstantaneous power requirements of the facility, a control unit 152determines an electrical load coupled to the ORC turbine-generatordevice 136. For example current sensors or facility energy monitors maybe used to determine the needs of the testing facility and command theORC turbine-generator device 136 to generate electricity as needed. Thecontrol unit 152 may also instruct or otherwise control the heated-fluidbleed pump 132 to supply heated coolant to the ORC turbine-generatordevice 136 based on the electrical load coupled to the ORCturbine-generator device, e.g., at a flow rate based on the electricalload. Further, the control unit 152 may determine the temperature of theheated coolant and further base the flow of heated coolant to the ORCturbine-generator device 136 on the temperature of the heated coolant.Similarly an optional control unit 154 may be provided to control thefill pump 148.

In practice the various control units 118, 152, 154 may be operatedmanually by a user. Alternatively, the control units may be automatic,such as where a specially programmed processor determines the electricalload, temperatures, pH levels, lubricity, flow rates, etc., and operatesthe components associated with the control units accordingly. Further,the control units 118, 152, 154 may be implemented separately, or one ormore of the control units 118, 152, 154 may be combined into one controlunit.

Further, the engine testing system 100 may include a bypass valve 156 inparallel to the ORC turbine-generator device 136. When the bypass valve156 is in a first position, the bypass valve 156 directs the heatedcoolant from the hot reservoir 128 to the ORC turbine-generator device136. Thus, during or after testing, hot coolant is pumped back throughthe ORC turbine-generator device 136 to the cold reservoir 116 asrequired creating on demand power. Comparatively, when in a secondposition, the bypass valve 156 directs the heated coolant from hotreservoir 128 to the conditioning system 144. Thus, when the bypassvalve 156 is in the second position, the ORC turbine-generator device136 is effectively removed from the closed loop of the primary coolantloop 130 (i.e., the engine testing system 100 does not performcogeneration when the bypass valve 156 is in the second position). Thus,if there is not enough cool coolant to perform an engine test, and thereis no demand for electrical power, the bypass valve 156 may be placed insecond position (i.e., the bypass position) to draw coolant to replenishthe cold reservoir 116.

Also, in certain embodiments, it is possible that at certain times, thecoolant may not be heated sufficiently to warrant transfer to the hotreservoir 128. For instance, during test set up, during low torquetesting, etc., the coolant exiting the rotary absorber 106 will be cool.Thus, to avoid adding cool coolant to the hot reservoir 128, a divertervalve 160 is used to divert the cool coolant to the conditioning system144. Here, the control unit 118 or other suitable control unit controlsthe diverter valve 160. In an example implementation, a thermocouple orother temperature measurement device can provide a temperaturemeasurement of the coolant to the control unit 118. Based upon thetemperature (or other factors), the control unit 118 controls thediverter valve 160 to route the coolant to either the hot reservoir 128or the conditioning system 144.

With the engine testing system 100, a user may test engines at differenttorque resistances and recover energy stored in the heated coolant at alater time. As mentioned above, the ORC turbine-generator device 136 maybe used to supply power to other components of the engine testing system100. As such, the heated coolant from one engine test may be stored inthe hot reservoir 128 to power components of the engine testing system100 during a later test. In some instances, the heated coolant from atest may be used to power components of the engine testing system 100during that same test.

Modularity:

The engine testing system 100 (or other systems set out more fullyherein) can be implemented in a modular form. Multiple cold reservoirs116 and hot reservoirs 128 may be plumbed together to create additionalcapacity to accommodate more than one test per day or to accommodatemore than one test cell. Capacity can be increased over time by addingreservoirs, ORC turbine-generator devices, heat exchangers,conditioners, etc. In larger facilities having multiple test cells, onlya single test cell may be initially outfitted with all or portions ofthe above energy re-capture schemes. Additional test cells may beconnected to the system over time. Likewise, additional energyre-capture methods may be implemented on specific test cells over time.Systems components such as heat exchangers, cold reservoirs, hotreservoirs, conditioning devices, ORC turbine-generator devices, etc.,can be shared among test cells. In certain embodiments, a systemcontroller is implemented to rout various test cells to various portionsof the system accordingly to a logical schema. Facility utilization,facility energy consumption, facility energy savings and otherperformance criteria can be monitored and displayed.

Power Generation:

Referring now to FIG. 2, a block diagram 200 illustrates components ofthe ORC turbine-generator device 136. As mentioned above, heated coolantis pumped by the heated-fluid bleed pump 132 into the ORCturbine-generator device 136 through the fluid inlet 138 and leavesthrough the fluid outlet 140 at a lower temperature. Essentially, energyfrom the heated coolant pumped through the ORC turbine-generator device136 is transferred via an evaporator 202 to an organic generator fluid.The evaporator 202 may be implemented as a first ORC liquid heatexchanger, such as an evaporator heat exchanger, that expands acondensed organic generator fluid based on heat from the heated coolantto create expanded organic generator fluid. The organic generator fluidis selected to have a low boiling temperature sufficiently below theworking temperature range of the coolant. In this regard, the evaporator202 expands the organic generator fluid, which changes the organicgenerator fluid from a liquid to a gaseous state inside the evaporator202. The organic generator fluid then cycles through a closed ORC loop204.

As illustrated, the expanded organic generator fluid exits theevaporator 202 and enters a turbine 206 via a generator-fluid inlet.Basically, the turbine 206 has a shaft 207 that rotates in response tothe expanded coolant entering the turbine 206. More particularly, theturbine 206 may be implemented as a radial flow, centrifugal flow orother type of turbine designed to operate with the particular organicfluid within the operating temperature and pressure ranges. The turbine206 converts the energy from the organic generator fluid to rotationalmechanical energy that rotates the shaft 207 of the turbine 206. Therotation of the shaft 207 of the turbine 206 generates electrical powerin a generator 208, and the power is output via an electrical output210.

After leaving the turbine 206 via a generator-fluid outlet, the organicgenerator fluid enters a condenser 212 via an expanded-generator-fluidinlet, where the organic generator fluid is condensed back to a liquidstate. For example, a second ORC heat exchanger 214 may be used to coolthe organic generator fluid, which condenses the organic generatorfluid. This second heat exchanger 214 may be a dry air heat exchangerthat transfers additional heat to the atmosphere. Alternatively, if anexternal source of cooling is available such as cold water from ageothermal well, river, lake, ocean or other source, the heat exchanger214 may be a water to liquid heat exchanger. Still further, other formsof cooling devices or heat exchangers 214 could be employed to condensethe generating fluid. A recirculation pump 216 pulls the organicgenerator fluid from a condensed-fluid outlet of the condenser 212 intoa generator-fluid inlet of the first evaporator 202 (first ORC heatexchanger), completing the ORC loop 204. This thermodynamic cycle isknown as an “Organic Rankine Cycle.”

A regenerator 218 is optionally used in the ORC loop 204 to reclaim heatbefore the organic generator fluid is condensed by the condenser 212.The regenerator 218 may be implemented as a third ORC heat exchangersuch as a counter-current heat exchanger. The regenerator 218 preheatsthe organic generator fluid before it is expanded within the evaporator202. In this regard, the ORC turbine-generator device 136 is made evenmore efficient.

The ORC turbine-generator device 136 uses a (preferably non-toxic)organic generator fluid such as a non-hydrofluorocarbon, fluorocarbon,etc., in the ORC loop 204 to convert heat from the heated coolant toelectrical power. This organic generator fluid is specificallyformulated to have properties that allow for optimal energy extractionwithin the operating temperature range of the stored coolant. Also, theorganic generator fluid allows the ORC turbine-generator device 136 togenerate electricity from the heated coolant (typically 60-94 degreesCelsius) whereas some power generating turbines require super-heatedsteam and function according to an ordinary Rankine cycle.

Because the primary coolant loop 130 is isolated from the ORC loop 204,the coolant and organic generator fluid never come into direct physicalcontact with each other. Instead, heat from the coolant is transferredto the organic generator fluid. Further, the neither the organicgenerator fluid nor the coolant are exposed to the atmosphere.

Additional Energy Capture Techniques:

When testing engines, heat may be derived in numerous forms, and is notlimited to waste shaft energy. By way of example, when testing internalcombustion engines, a combustible mixture of fuel (e.g., gasoline,kerosene, ethanol, etc.) and oxidant (e.g., atmospheric air, oxygen,etc.) provides the input energy to produce shaft energy (rotation andtorque) or thrust necessary to perform useful work. However, typicalinternal combustion engines are inefficient, converting less than halfof the input energy from the combustible fuel air mixture into usefulwork. The resulting waste energy is released in the form of convectiveor radiant heat directly from the engine, in the form of hot exhaustgases, or a combination thereof. Other mechanical losses, such as fromfriction are also typically present in these engines.

Also, when testing shaft power internal combustion engines, e.g.,reciprocating piston engines, rotary or Wankle engines, gas turbines,turbo-shaft jet engines, and turbo-prop jet engines, exhaust gaseshaving both heat and thrust are produced. In conventional systems, suchexhaust gases contribute to C0₂ (greenhouse gas) and contain other toxicand non-toxic compounds and particulates that are atmosphericpollutants. Correspondingly, thrust engines, e.g., jet engines,turbo-fan jet engines, etc., produce thrust to perform the intendedwork. Here, fuel and air are converted to thrust that propels anaircraft or some other vehicle. However, according to various aspects ofthe present disclosure herein, conventionally wasted energy, e.g.,including exhaust gases, convection, radiant heat, mechanical lossesfrom friction, etc., can be captured by the engine testing system 100.

As will be described in greater detail herein, for certain types ofinternal combustion engines that have liquid cooling circuits, thecoolant is directed to a heat exchanger which transfers the energy fromthe coolant to another coolant, e.g., heated water, which can be storedin a hot reservoir. As another example, thrust is converted torotational mechanical energy by causing the exhaust gases to drive aturbine-generator that converts thrust energy to rotational shaft powerthat in turn drives a generator which produces electricity. Moreover, inexample implementations, exhaust heat is collected by causing theexhaust gasses to be directed through a gas to liquid heat exchangerwhere the energy is transferred to a coolant. Accordingly, waste shaftenergy, waste cooling energy and waste exhaust energy represent examplesof energy that can be recaptured by the systems and methods herein.

Example Energy Capture System Combination:

Referring to FIG. 3, a block diagram of an example engine testing system300 illustrates several ways to reclaim waste energy from an enginetest. The engine testing system 300 includes many of the same systemcomponents as the engine testing system 100 and thus all featuresdescribed above are applicable and incorporated into the engine testingsystem 300. As such, like components are indicated with like referencenumbers and the discussion of components from FIG. 1 is not repeated.Moreover, some components from FIG. 1 are omitted for clarity, but inpractice, may be included in an implementation of the engine testingsystem 300.

Hot Reservoir Heating:

As illustrated in FIG. 3, in some, but not all embodiments, the enginetesting system 100 of FIG. 1 is augmented by modifying the hot reservoir128 to include a heating element 302 (e.g., a resistive heatingelement). The heating element 302 is coupled to one or more powersources through an electrical switch 304.

More particularly, a first circuit 306 electrically couples theelectrical switch 304 to the heating element 302. A second circuit 308electrically couples the electrical switch 304 to one or more (external)devices, e.g., to power components of the engine testing system 300, topower other components within the testing facility, to put power back onthe main power grid, other desired use or combinations thereof.Moreover, the electrical switch 304 can be controlled by a control unit309, e.g., a programmable logic controller (PLC), computer, or otherprocessing device.

The control unit 309 is illustrated as a separate control device forsake of convenience in the block diagram, and to clearly illustrate thelogical function of controlling aspects of the electrical switch 304.However, in some, but not all embodiments, all controllers logicallyillustrated herein, are implemented by a common, central controller.Thus, in these embodiments, the control unit 309 is integrated withother processing devices, such as any one or more of the control units118, 152, 154, etc.

The electrical switch 304 can be controlled to operate in a first statewhere incoming electrical power is routed to the heating element 302 viathe first circuit 306. The electrical switch 304 can be operated in asecond state where incoming electrical power is routed to one or moredevices via the second circuit 308. The electrical switch 304 may alsobe operated in a third state where incoming electrical power is routedto both the first circuit 306 and the second circuit 308. Still further,depending upon the sophistication of the electrical switch 304,electrical output may be routed to other outputs as the applicationdictates.

The electrical output 210 of the ORC turbine-generator device 136 cancouple to the electrical switch 304, or the electrical output 210 of theORC turbine-generator device 136 can be isolated from the electricalswitch 304. However, there are certain advantages to connecting theelectrical output 210 to the electrical switch 304. For instance, theelectrical output 210 may be defined by a circuit from an electricaloutput of the ORC turbine-generator device 136 to the electrical switch304 such that the ORC turbine-generator device 136 can provideelectrical power to the first circuit 306, the second circuit 308, orboth, depending upon a state of the electrical switch 304.

By way of example, there may be times when there is little or no demandfor electricity, testing is necessary, and there is insufficient coolantin the cold reservoir 116 to facilitate testing. However, if the coolantin the hot reservoir 128 is sufficiently warm to operate the ORCturbine-generator device 136, the warm coolant is pumped to the ORCturbine-generator device 136 and the generated electricity is routed viathe electrical switch 304 via the circuit 306 to the heating element 302located inside the hot reservoir 128. Accordingly, coolant is drawn fromthe hot reservoir 128 to replenish the cold reservoir 116 via theprimary coolant loop 130. Moreover, the coolant that remains in the hotreservoir 128 receives additional heat via the heating element 302. Thisis a form of regeneration and will improve the overall efficiency of thesystem in periods of low demand by not entirely wasting the storedenergy by simply cooling the warm water without extracting any usefulwork. The volume of warm coolant is reduced but the temperature of theremaining coolant is increased.

Should the coolant in the hot reservoir 128 become too cool to operatethe ORC turbine-generator device 136, the bypass valve 156 directs thelukewarm coolant directly to the conditioning system 144 (secondary heatexchanger) and back to the cold reservoir 116. Thus, the bypass valve156, electrical switch 304, and other necessary devices are controlledby a system controller (e.g., control unit 309) that directs electricityto be used by the facility or for regenerative heating. Note here thatcoolant circulates through the primary coolant loop 130, as describedwith reference to FIG. 1.

Thrust Exhaust Heating:

As illustrated in FIG. 3, in some, but not all embodiments, the enginetesting system 100 of FIG. 1 is augmented to capture exhaust gases,e.g., in the form of thrust such as when testing thrust engines or shaftengines which produce waste thrust as a by-product.

As illustrated, the exhaust of an engine 102 under test is directed to aturbine-generator system having a turbine-generator 310, which functionsas an energy conversion device. The turbine-generator 310 generateselectrical power using a flow of exhaust gases from the engine 102 whilethe engine 102 is running. As the gases pass through theturbine-generator 310, an internal turbine rotates, creating electricalpower, which is directed toward the electrical switch 304 via a thirdcircuit 312.

The electrical switch 304 can thus output the energy from theturbine-generator 310 as electricity via circuit 308. Also, whencombined with the heating element 302 of the Hot Reservoir Heatingembodiment described above, the electricity provided by theturbine-generator 310 can be directed by the electrical switch 304 viacircuit 306 to the heating element 302 to provide additional heating ofthe coolant stored in the hot reservoir 128. Thus, the turbine-generator310 receives exhaust gases from the engine testing operation andconverts the exhaust gases into electrical power that is selectivelycoupled to the heating element 302 that heats the coolant in the hotreservoir 128.

In certain embodiments, the turbine-generator 310 is controlled by acontrol unit 313. For instance, the control unit 313 can receivefeedback as to the temperature of the fluid stored in the hot-reservoir128. If the temperature is above a predetermined threshold, and there isno demand for electricity, the control unit 313 can controlturbine-generator 310 to not produce electricity. Alternatively, thecontrol unit 313 can control the electrical switch 304 to re-routeelectricity provided via circuit 312 from the circuit 306, which feedsthe heading element 302, to a different output.

The control unit 313 is illustrated as a separate control device forsake of convenience in the block diagram, and to clearly illustrate thelogical function of controlling aspects of the turbine-generator 310.However, in practice, the control unit 313 may be integrated with, orotherwise implemented by the same control circuitry that controls theelectrical switch 304, e.g., by integrating with the control unit 309.Still further, in illustrative aspects, all controllers logicallyillustrated herein, are implemented by a common, central controller.Thus, in these embodiments, the control units 313 and 309 are integratedwith other processing devices, such as any one or more of the controlunits 118, 152, 154, etc.

Exhaust Loop Heating:

As illustrated in FIG. 3, in some, but not all embodiments, the enginetesting system 100 of FIG. 1 is augmented to capture energy from exhaustgases. For instance, in an illustrative implementation, a separateexhaust heat system is defined by components within a high temperaturecoolant loop 314 (exhaust coolant loop). The exhaust coolant loop usesheat from the exhaust of an engine 102 under test as a source of energyfor cogeneration. For instance, the exhaust heat system can include agas to liquid heat exchanger 316 (e.g., an exhaust coil) that transferswaste energy in the form of heated exhaust gases from the engine testingoperation, to heat that heats an exhaust coolant. The exhaust heatsystem also includes an exhaust electrical power generating device 318.Here, the high temperature coolant loop 314 couples the heated exhaustcoolant from the gas to liquid heat exchanger 316 to the exhaustelectrical power generating device 318, back to the gas to liquid heatexchanger 316. In this regard, the high temperature coolant loop 314 isa relatively higher temperature coolant loop that is separate andindependent from the primary coolant loop 130.

The electrical power generating device 318 functions as an energyconversion device. For instance, the electrical power generating device318 may be implemented as an ORC turbine-generator device (referred toherein as an exhaust ORC turbine-generator device), where the heat isused to expand an internal organic generator fluid of the exhaust ORCturbine-generator device in a manner analogous to the ORCturbine-generator device 136, described in greater detail with referenceto FIG. 1 and FIG. 2. However, the temperature of the coolant exitingthe heat exchanger 316 in the exhaust coolant loop 314 is likely to besignificantly higher than the temperature of the heated coolant from therotary absorber 106 in the primary coolant loop 130. Accordingly, theorganic generator fluid internal to the exhaust ORC turbine-generatordevice will be different than the organic generator fluid in the ORCturbine-generator device 136. For instance, in an illustrative example,the organic generator fluid in the exhaust ORC turbine-generator devicewill function from about 150 to 1500 degrees Celsius or higher comparedto a temperature range of 60-94 degrees Celsius for the organicgenerator fluid used by the ORC turbine-generator device 136.

In an alternative embodiment, the electrical power generating device 318is implemented as a turbine-generator device. As such, theturbine-generator device need not be an ORC turbine-generator device,per se. For instance, in an illustrative embodiment, the coolant isgasified and super-heated in the cooling loop. As such, the heated fluidcan be used directly by the turbine, without using an evaporative heatexchanger such as the evaporator 202, described with regard to FIG. 2.

The coolant in the exhaust coolant loop 314 is pumped by an exhaust looppump 320 back to the heat exchanger 316. Thus, as shown the exhaustcoolant loop 314 is a closed loop system. Moreover as shown there is nostorage of the coolant used in the exhaust coolant loop 314.

In a normal mode of operation, the exhaust coolant may not requirefurther cooling after it exits the exhaust of the exhaust ORCturbine-generator device. For example, in efficient operation, there isno desire to waste already recovered waste energy. Thus, in the normalmode of operation, the exhaust coolant pump 320 pumps the coolantdirectly back to the exhaust heat exchanger 316. In embodiments where asecondary exhaust coolant heat exchanger 322 is provided in the exhaustcoolant loop 314, the secondary exhaust coolant heat exchanger 322 istypically bypassed in the normal mode, e.g., using a diverter valve 323switch that is set to a bypass position.

However, in some modes of operation, there may be no demand forelectrical power. In some embodiments, the control unit 309 controls theelectrical power generating device 318 to cool the exhaust coolant, butnot to produce electricity, such as by disabling the turbine within theturbine-generator device. Here, the exhaust coolant heat exchanger 322may not be required.

In other embodiments, the exhaust coolant is caused to bypass theexhaust ORC turbine-generator device by switching an optional bypassvalve 324 to a bypass position. In this case, the coolant in the exhaustcoolant loop 314 bypasses the exhaust ORC turbine-generator device 318and is pumped by the exhaust loop coolant pump 320 to a secondaryexhaust coolant heat exchanger 322 by switching the diverter valve 323to a cooling (non-bypass) position. The secondary exhaust coolant heatexchanger 322 may be a dry-air heat exchanger or some other type of heatexchanger that ensures the exhaust loop coolant is at a sufficiently lowtemperature before entering the exhaust heat exchanger 316 (e.g.,cooling coil) to avoid an over temperature condition.

Thus, by controlling the diverter valve 323 and the bypass valve 324,e.g., using a suitable controller such as control unit 309, the exhaustcoolant can be utilized by the electrical power generating device 318,the secondary exhaust coolant heat exchanger 322, or a combination ofthe two. Here, the diverter valve 323 and the bypass valve 324 may beanalogous to the bypass valve 156 described in greater detail withreference to FIG. 1. In an alternative embodiment where the secondaryexhaust coolant heat exchanger 322 is not provided, the controller,e.g., control unit 309 may control the exhaust ORC turbine-generatordevice 318 to cool the exhaust coolant, but not to produce electricity,such as by commanding the generator within the ORC turbine-generatordevice to not produce electricity.

In normal mode, the generated electrical power from the exhaust ORCturbine-generator device 318 flows to the electrical switch 304 along acircuit 325. The electrical switch 304 can output the energy via circuit308. Also, when combined with the heating element 302 of the HotReservoir Heating embodiment described above, the electricity providedby the exhaust ORC turbine-generator device 318 can be directed by theelectrical switch 304 via circuit 306 to the heating element 302 toprovide additional heating of the coolant stored in the hot reservoir128. Thus if there is no demand for electricity, the recovered wasteenergy is stored as heat energy within the hot reservoir 128. Moreover,where both the turbine-generator 310 and the heat exchanger 316 areutilized, the electrical switch 304 can route electricity received viacircuit 312 and via circuit 325 in any manner as set out more fullyherein, either in combination, or independently. As such, the electricalswitch 304 may route electricity to the circuit 306, to the circuit 308,or to both.

As shown in FIG. 3, in embodiments where both the turbine-generator 310and the heat exchanger 316 are utilized, the heat exchanger 316 is afterthe turbine-generator 310 relative to the direction of flow of exhaustgases. However the heat exchanger 316 may be before theturbine-generator 310 relative to the flow of exhaust gases.

Engine Coolant Loop First Variation:

As illustrated in FIG. 3, in some, but not all embodiments, the enginetesting system 100 of FIG. 1 is augmented to capture energy from enginecoolant using a coolant loop 326 (engine coolant loop).

The engine 102 under test may utilize an engine coolant to keep theengine cool under normal operation. This coolant can be used to extractheat away from the engine 102, which can be captured and converted tousable energy. Basically, engine coolant heated by the engine 102 duringa testing operation (e.g., via an engine heat exchanger) is conveyed viathe engine coolant loop 326 to a secondary heat exchanger 328 providedwithin the ORC turbine-generator device 136. Thus, the components of theengine coolant loop 326 cooperate to define an energy conversion device.The secondary heat exchanger 328 is provided adjacent to the evaporator202 of the ORC turbine-generator device 136 associated with the rotaryabsorber 106. As such, the organic generator fluid of the ORCturbine-generator device 136 may be expanded by the heated coolantcirculating through the primary coolant loop 130, the engine coolantcirculating through the engine coolant loop 326, or both. After heat istransferred from the engine coolant to the organic generator fluid ofthe ORC turbine-generator device 136, the engine coolant may be furtherprocessed by an optional conditioning system 330 before the enginecoolant is sent back to the engine 102 under test. The conditioningsystem 330 can include features analogous to the conditioning system 144described more fully herein, as the specific application dictates.

In some embodiments, the engine coolant will typically range below 140degrees Celsius. As such, both the engine coolant loop 326 and theprimary coolant loop 130 may use the same ORC turbine-generator device136. Regardless, the engine coolant loop 326 may include a bypass valve332 to remove the ORC turbine-generator device 136 from the enginecoolant loop 326 in a manner analogous to the bypass valve 156 describedwith reference to FIG. 1.

Engine Coolant Loop Second Variation:

Referring to FIG. 4, in some, but not all embodiments, the enginetesting system 100 of FIG. 1 and/or the engine testing system 300 ofFIG. 3 is augmented as illustrated in the engine testing system 400 tocapture energy from engine coolant using a coolant loop 402 (enginecoolant loop). The engine testing system 400 includes many of the samesystem components as the engine testing system 100 and/or engine testingsystem 300, thus all features described above are applicable andincorporated into the engine testing system 400. As such, likecomponents are indicated with like reference numbers and the discussionof components from FIG. 1 through FIG. 3 is not repeated. Moreover, somecomponents from FIG. 1 through FIG. 3 are omitted for clarity, but inpractice, may be included in an implementation of the engine testingsystem 400. In this regard, a practical implementation of the enginetesting system 400 may include any one or more of the Thrust ExhaustHeating, Exhaust Loop Heating, and Engine Coolant Loop First Variationembodiments in addition to the components of the Engine Coolant LoopSecond Variation as set out more fully herein.

This embodiment is largely analogous to the Engine Coolant Loopembodiment above in FIG. 3 except that the engine coolant loop 402circulates heated coolant (from an engine heat exchanger) through aturbine-generator device (also referred to herein as an engineturbine-generator device 404) that is separate and distinct from the ORCturbine-generator device 136 used by the primary coolant loop 130. Thus,the components of the engine coolant loop 402 cooperate to define anenergy conversion device.

Although not shown for sake of clarity, the engine testing system 400can also optionally include the components and features described withreference to the Thrust Exhaust Heating embodiments, Exhaust LoopHeating embodiments, or a combination thereof.

The engine coolant loop 402 uses heat extracted from a heat exchanger ofan engine 102 under test as a source of energy for cogeneration. Forexample, heated coolant from the engine 102 flows via the engine coolantloop 402 to an engine turbine-generator device 404. For instance, wherethe turbine-generator device 404 is an ORC turbine-generator device, theheat is used to expand an internal organic generator fluid of theexhaust ORC turbine-generator device in a manner analogous to the ORCturbine-generator device 136 described in greater detail with referenceto FIG. 1 and FIG. 2.

In some embodiments, the coolant in the engine coolant loop 402 ispumped by an engine loop pump 406 back directly to the engine heatexchanger. However, in alternative embodiments, the coolant in theengine coolant loop 402 is pumped by the engine loop pump 406 to anoptional engine coolant conditioning system 408 that conditions thecoolant, whereupon the coolant is returned to the engine heat exchanger.

The engine coolant conditioning system 408 implements one or moreanalogous functions as the conditioning system 144 of FIG. 1. As shown,the engine coolant loop 402 is a closed loop system. Moreover, as shownthere is no storage of the coolant used in the engine coolant loop 402.

The generated electrical power from the engine turbine-generator device404 flows to the electrical switch 304 along a circuit 412. Theelectrical switch 304 can output the energy as electricity via circuit308. Also, when combined with the resistive heating element 302 of theHot Reservoir Heating embodiment described above, the electricityprovided by the engine turbine-generator device 404 can be directed bythe electrical switch 304 via circuit 306 to the heating element 302 toprovide additional heating of the coolant stored in the hot reservoir128. Thus if there is no demand for electricity, the recovered wasteenergy is stored as heat energy within the hot reservoir 128.

In some embodiments, there may be no demand for electrical power. Assuch, the engine coolant is caused to bypass the engineturbine-generator device 404 by switching bypass valve 410 to a bypassposition. In this case, the coolant in the engine coolant loop 402 ispumped by the engine loop pump 406 to the engine coolant conditioningsystem 408 (implemented as a secondary engine heat exchanger) byswitching a diverter valve 409 to a cooling position. The engine coolantconditioning system 408 may be a dry-air heat exchanger or some othertype of heat exchanger that ensures the engine loop coolant is at asufficiently low temperature before entering the engine cooling coil toavoid an over temperature condition.

The diverter valve 409 and the bypass valve 410 are analogous to thediverter valve 323 and the bypass valve 324 described with reference toFIG. 3. In this regard, by controlling the diverter valve 409 and thebypass valve 410, e.g., using a suitable controller such as control unit309, the engine coolant can be utilized by the engine turbine-generatordevice 404, the engine coolant conditioning system 408, or a combinationof the two. In an alternative embodiment where the engine coolantconditioning system 408 is not provided, the controller, e.g., controlunit 309 may control the engine turbine-generator device 404 to cool theexhaust coolant, but not to produce electricity, such as by disablingthe turbine within the turbine-generator device.

Thrust Engine Capture:

Referring to FIG. 5, in some, but not all embodiments, the enginetesting system 100 of FIG. 1, the engine testing system 300 of FIG. 3,the engine testing system 400 of FIG. 4, or a combination thereof, isaugmented (or simplified) as illustrated in the engine testing system500 to capture energy from a thrust engine. The engine testing system500 includes many of the same system components as the engine testingsystem 100, engine testing system 300, engine testing system 400, orcombinations thereof, thus all features described above are applicableand incorporated into the engine testing system 500. As such, likecomponents are indicated with like reference numbers and the discussionof components from FIG. 1 through FIG. 4 is not repeated. Moreover, somecomponents from FIG. 1 through FIG. 4 are omitted for clarity, but inpractice, may be included in an implementation of the engine testingsystem 500.

The engine testing system 500 is well suited for testing thrust engines.Since there is no engine shaft that requires a load, there is no needfor the rotary absorber 106 or cold reservoir 116 of the engine testingsystem 100 of FIG. 1. The conditioning system 144 of FIG. 1 may also beoptionally omitted as well. In this regard, a practical implementationof the engine testing system 500 may include any one or more of theThrust Exhaust Heating, Exhaust Loop Heating, Engine Coolant Loop FirstVariation, and Engine Coolant Loop Second Variation embodiments as setout more fully herein.

In the engine testing system 500, the primary coolant loop 502 runs fromthe hot reservoir 128 to a pump 504 that delivers the heated coolant tothe ORC turbine-generator device 136. The coolant exits the ORCturbine-generator device 136 and is conveyed by pump 506 directly backto the hot reservoir 128. Here, the components of the primary coolantloop 502 cooperate to form an energy conversion device.

In this implementation, the ORC turbine-generator device 136 (e.g., viathe engine coolant loop 326 or a reservoir loop 502), theturbine-generator 310, the exhaust ORC turbine-generator device 318, orcombinations thereof, may be used to heat the hot reservoir 128 asdescribed more fully herein, depending upon which one or more of thetechnologies are in the particular implementation of the engine testingsystem 500.

For instance, the engine testing system 500 may include a bypass valve510, which operates in a manner analogous to the bypass valve 156described more fully herein, to circulate heated coolant in thereservoir loop 502 back to the hot reservoir 128.

In certain testing operations, it may be undesirable to attempt toharness the thrust generated by the shaftless engine as electricalpower, e.g., because to do so may interfere with the testing of theengine. However, the thrust can be used to provide heat to the coolantin the hot reservoir 128 via the circuit 306 and heating element 302.Moreover, the heat and gas flow of the exhaust may still be harnessedfor electrical power of the shaftless engine, as described above.

In the engine testing system 500, the hot reservoir 128 is sized basedupon estimated testing schedule usage and power demands. During testing,electricity can be diverted to the facility, e.g., via the circuit 308and/or to the heating element 302 via the circuit 306, as required, in amanner analogous to that described more fully herein. As described ingreater detail with regard to FIG. 3, there may be situations wherethere is no demand for electricity. In this regard, certain embodimentsmay be adjusted or otherwise configured, such as by bypassing theexhaust ORC turbine-generator device 318 using valve 324 and divertingthe coolant through heat exchanger 322 using diverter valve 323. As yetanother alternative, the controller (e.g., control unit 309) may commandthe generator to not produce electricity. As another example, the ORCturbine-generator device 136 may be routed to the electrical switch 304such that electrical energy can be routed to the heating element 302.

Notably, in certain implementations waste energy from intermittentengine testing operations is used by a first ORC turbine-generatordevice 318 to heat coolant in a hot reservoir 128 so that the heatedcoolant can be extracted on demand or as otherwise needed to be used bya second ORC turbine-generator device 136 to generate on demandelectricity that can be utilized by the corresponding facility, by thecomponents of the testing engine testing system 500, fed back to thepower grid, etc.

Generator/Dynomometer:

Referring to FIG. 6, in some, but not all embodiments, the enginetesting system 100 of FIG. 1, the engine testing system 300 of FIG. 3,the engine testing system 400 of FIG. 4, the engine testing system 500of FIG. 5, or a combination thereof, is augmented as illustrated in thesystem 600 to capture energy from a using an electric generating devicethat converts shaft rotation to electrical energy. The system 600includes many of the same system components as the engine testing system100, engine testing system 300, engine testing system 400, enginetesting system 500, or combinations thereof, thus all features describedabove are applicable and incorporated into the system 600. As such, likecomponents are indicated with like reference numbers and the discussionof components from FIG. 1 through FIG. 5 is not repeated. Moreover, somecomponents from FIG. 1 through FIG. 5 are omitted for clarity, but inpractice, may be included in an implementation of the system 600. Inthis regard, a practical implementation of the system 600 may includeany one or more of the Thrust Exhaust Heating, Exhaust Loop Heating,Engine Coolant Loop First Variation, and Engine Coolant Loop SecondVariation embodiments as set out more fully herein.

In certain situations, a rotary absorber 106 may be a device that doesnot directly convert the rotational shaft energy to a form or heat thatis carried away by a coolant. For instance, in an illustrativeembodiment, the rotary absorber 106 is implemented as an electricgenerating device 606 that converts the shaft power from the rotation ofthe output shaft 104 of the engine 102 directly to electricity. In anexample embodiment, the electric generating device 606 is implemented asan electric generator. In an alternative embodiment, the electricgenerating device 606 is implemented as an electric dynamometer.Regardless, an electrical load is applied to the output of the electricgenerating device 606 in order to produce resistance. Here, the electricgenerating device 606 and electrical load cooperate to define an energyconversion device.

In a first illustrative implementation, the electrical load 608 isimplemented as a resistor bank with liquid or air heat exchange. In thisexample, a resistor bank loop 610 is used to circulate a working fluidfrom the resistance bank heat exchanger to a secondary heat exchanger612 of an ORC turbine-generator device 614. A pump 616 is used to routethe working fluid from the ORC turbine-generator device 614 back to theresistance heat exchanger associated with the resistor bank.

As with the Engine Coolant Loop First Variation example of FIG. 3 and/orthe Thrust Engine Capture example of FIG. 5, a hot-reservoir 128 storesa heated coolant, which is also coupled to the ORC turbine-generatordevice 614 (analogous to the ORC turbine-generator device 136 discussedmore fully herein) via a heated coolant loop 618. A pump 620 may be usedto return the coolant back to the hot-reservoir 128. In this regard, theheated coolant of the heated coolant loop 618 is separate from, but inseries with the working fluid of the resistor bank loop 610 within theORC turbine-generator device 614. For instance, as schematicallyillustrated, the secondary heat exchanger 612 is provided adjacent tothe conventional evaporator 202 of the ORC turbine-generator device 614.As such, the organic generator fluid of the ORC turbine-generator device614 may be expanded by the heated coolant circulating through theresistor bank loop 610, the heated coolant loop 618, or both.

The output of the ORC turbine-generator device 614 may be provided via acircuit 622 to the electrical switch 304 described more fully herein.Alternatively, the output of the electric generating device 614 may bedirected to other devices, or a combination of both as describedpreviously.

Moreover, a bypass valve 624 may be provided to bypass the heatedcoolant in the heated coolant loop 618 from entering the ORCturbine-generator device 614. Similarly, a bypass valve 626 may beprovided to bypass the working fluid in the resistor bank loop 610 fromentering the secondary heat exchanger 612 of the ORC turbine-generatordevice 614. In a manner analogous to that described more fully herein,the bypass valve 624, bypass valve 626, or both may be controlled, e.g.,via controller 632 to direct the flow of fluids according to the systemrequirements. In a manner analogous that described more fully herein,the controller 632 is shown logically as a separate feature. However, inpractice, the controller 632 may be integrated with the control unit 309or other controllers described more fully herein.

The system 600 can be simplified by omitting the electrical load 608,resistor bank loop 610, secondary heat exchanger 612, and pump 616. Inthis regard, the heating element 302 can serve as the resistive load byrouting, the electric generating device 606 through the electricalswitch 304 to the heating element 302. The system 600 can be simplifiedeven further by omitting the electrical switch 304, thus routing theoutput of the electric generating device 606 directly to the heatingelement 302.

There may be times when there is no demand for electricity and the hotreservoir 128 is too hot (e.g., above a pre-determined thresholdtemperature). Under this scenario, power should be diverted, e.g., to aseparate load bank 630. The load bank 630 may be air or liquid cooled byway of example. The load bank 630 may also be useful or otherwiserequired to facilitate emergency or sudden stops, or to prevent arun-away condition if the switch gear fails. Here, a controller 632controls the electric generating device 606, the electrical switch 304,or a combination thereof to divert power to the load bank 630. Thecontroller 632 can also be used to control the electric generatingdevice 606, e.g., to turn the device on or off. In an analogous mannerto that described more fully herein, the controller 632 may be part of alarger central control system, or the controller 632 may be a separatecontrol device.

Method of Collecting and Using Waste Energy Using a Rotary Absorber:

FIG. 7 is a flow chart illustrating a method 700 for testing an engine,which may be performed by the systems of FIGS. 1-6. At 710, cool coolantis stored in a cold reservoir. (e.g., one or more storage tanks).

At 720, cool coolant from the cold reservoir is used carry away heatfrom a shaft of an engine under test via a rotary absorber, which heatsthe cool coolant into heated coolant. At 730, the heated coolant isstored in a hot reservoir, which may be one or more insulated storagetanks. The heated coolant may be supplied to the hot reservoir by aheated-fluid supply pump, which in turn may be controlled by a controlunit that determines a required flow rate for the test and sets theheated-fluid supply pump to that flow rate. The control unit may be thesame control unit as the cool-fluid control unit may work in conjunctionwith the cool-fluid control unit, or may be independent of thecool-fluid control unit.

At 740, heat from the heated coolant is converted into electrical powerusing an Organic Rankine Cycle (ORC) turbine-generator device, whichcools the coolant to create warm coolant, as described more fullyherein. The amount of heated coolant supplied to the ORCturbine-generator device may be determined by detecting an electricalload on the ORC turbine-generator device and basing a flow rate on thatelectrical load.

At 750, the warm coolant is conditioned with a conditioning system bycooling the warm coolant further to create cool coolant, which is storedback in the cold reservoir at 710. A cool-fluid fill pump may be used toreturn the coolant from the conditioning system to the cold reservoir.The conditioning system may include a dry-air heat exchanger to removeand distribute heat to the air, or the conditioning system may use someother form of heat exchanger with an external cooling supply. Further,the conditioning system may condition the coolant in other ways. Forexample, the coolant may be treated to maintain a proper pH level andphysical chemistry for engine testing. As another example, the coolantmay be treated to maintain a proper lubricity for engine testing. As afurther example, the coolant may be filtered to remove any impuritiesintroduced anywhere along the method.

Any or all of the pumps, control units, conditioning systems, etc., maybe powered by the electrical power produced by the ORC turbine-generatordevice using heated coolant that was stored in the hot reservoir duringthe instant test or any previous test. Further, the ORCturbine-generator device may be bypassed by directing the heated coolantthrough a bypass valve.

Moreover, the electrical power may be supplemented by other generators.For example, heat from the exhaust of the engine under test or from theengine itself may be reclaimed as heat. As another example, flow ofexhaust gases may be used to rotate a turbine-generator to createelectrical power.

The systems and methods described herein may be used to store energy forlater use in cogeneration, because the heated coolant is stored in thehot reservoir to bleed off for later use. This cogenerated electricitymay be used to offset some of the power requirements of the system orother systems at a testing facility.

As an example implementation, a turbo-shaft jet engine to be tested maybe “dressed” by installing a direct mounted rotary absorber and otheritems such as intake bell, starter, throttle servo, harnesses, etc. Thedressed engine including the rotary absorber is then transported as anassembled unit into the test cell for testing, e.g., using an overheadgantry or other suitable method. Once in the test cell, final hookupsmay be made. This results in a very efficient workflow and requiresrelatively small test cells.

FIG. 8 is a flow chart illustrating another method 800 for testing anengine, which may be performed by the systems of FIGS. 1-6. Referring toFIG. 8, according to further aspects of the present disclosure, a methodof performing engine testing operations comprises using at 810, a firstenergy conversion device for converting waste energy derived fromintermittent engine testing operations into heat that heats a coolant.The method also comprises using at 820, a second energy conversiondevice for converting waste energy derived from intermittent enginetesting operations into usable energy, where the second energyconversion device operates independently of the first energy conversiondevice. The method also comprises utilizing at 830, a hot reservoir forstoring the coolant heated as a result of the intermittent enginetesting operations. The method still further comprises using at 840, anelectrical power generating device coupled to the hot reservoir, forconverting heat extracted from the coolant stored in the hot reservoirinto on-demand electrical power. The method thus defines a primarycoolant loop that couples the coolant from the hot reservoir to theelectrical power generating device and from the electrical powergenerating device to the optional conditioning system.

In an example implementation, the method comprises implementing thefirst energy conversion device as a rotary absorber that provides avariable resistance to rotation of a shaft of an engine under testduring the engine testing operation, producing waste energy that heatsthe coolant transferred from a cold reservoir to the hot reservoir. Inaddition or alternatively, the method comprises implementing one of theenergy conversion devices as an electric generating device that convertsshaft power from the rotation of the shaft of the engine under test toelectricity, and applying an electrical load to an output of theelectric generating device in order to produce resistance.

In addition to any of the above example implementations, oralternatively, the method comprises implementing the second energyconversion device as a turbine-generator that receives exhaust gasesfrom the engine testing operation and converts the exhaust gases intoelectrical power.

In addition to any of the above example implementations, oralternatively, the method may comprise implementing the second energyconversion device as a gas to liquid heat exchanger and an electricalpower generating device. The heat exchanger transfers energy fromexhaust gases from the engine testing operation to heat that heats anexhaust coolant. The heat from the exhaust coolant is converted toelectricity by the exhaust electrical power generating device. Here, themethod comprises forming a high temperature coolant loop that couplesthe heated exhaust coolant from the gas to liquid heat exchanger to theexhaust electrical power generating device, back to the gas to liquidheat exchanger, where the high temperature coolant loop is independentof the primary coolant loop.

In addition to any of the above example implementations, oralternatively, the method may comprise implementing the second energyconversion device as an engine heat exchanger that transfers wasteenergy in the form of engine heat to an engine coolant that carries awayheat from the engine under test, and a secondary heat exchanger in anORC turbine-generator device. Here, heat drawn by the ORCturbine-generator device for conversion to electricity is from acombination of heat from the engine coolant and heat from the coolantfrom the hot reservoir.

In addition to any of the above example implementations, oralternatively, the method may comprise implementing the second energyconversion device as an engine heat exchanger that transfers wasteenergy in the form of engine heat to an engine coolant that carries awayheat from the engine under test, and an engine ORC turbine-generatordevice that converts heat from heated engine coolant into electricalpower.

FIG. 9 is a flow chart illustrating yet another method 900 for testingan engine, which may be performed by the systems of FIGS. 1-6. Referringto FIG. 9, according to still further aspects of the present disclosure,an engine testing method 900 comprises using at 910, an electricgenerating device (e.g., a turbine-generator or a dynomometer) forconverting intermittent waste energy of an engine under test, intoelectrical power. The method also comprises using at 920, a hotreservoir to store heated coolant, and using at 930, an Organic RankineCycle (ORC) turbine-generator device for converting heat extracted fromthe heated coolant from the reservoir into usable electricity. Themethod defines a primary coolant loop arranged such that heated coolantflows from the hot reservoir to the ORC turbine-generator device, whichconverts heat from heated coolant into electrical power. The method alsocomprises using a resistive load coupled to the electric generatingdevice for converting electrical energy from the electric generatingdevice into heat that is utilized to heat the coolant.

The method may comprise implementing the resistive load as a heatingelement that heats the coolant in the hot reservoir. As another example,the method may comprise coupling the resistive load to a heat exchangerthat transfers heat from the resistive load to a heated working fluid,and using a second loop that transfers the heated working fluid to theORC turbine-generator device. Still further, the method may compriseusing an electric switch that receives the electrical power from theelectric generating device and selectively couples the electrical powerto a select one of the resistive load and a separate load bank.

Configurations:

The energy capture approaches described more fully herein, including thePrimary Waste Energy Capture, Hot Reservoir Heating, Thrust ExhaustHeating Exhaust Loop Heating, Engine Coolant Loop (both variations),Thrust Engine Capture, and Generator/Dynomometer variations can beutilized alone or in any of combination of energy capture approaches,depending upon testing system requirements. Moreover, an overall systemconfiguration can be simplified where less than all of the energycapture approaches are utilized, such as by omitting features that areunique to the non-utilized energy capture approach.

Miscellaneous Considerations:

In an example implementation, in order to capture the maximum amount ofenergy during an engine testing operation multiple heat exchanger loops(e.g., three or more loops) are utilized. For instance, a brake coolant(e.g., water) may be used in the primary coolant loop 130 to captureenergy based upon the fluid passing through the rotary absorber 106. Anexhaust coolant loop 314 may utilize an exhaust gas transfer (e.g.,organic heat transfer fluid) to capture energy from exhaust from theengine during testing. Engine coolant (e.g., glycol water mixture) maybe utilized in an engine coolant loop 326 to capture energy utilized tocool the engine under test.

The loops 130, 314, 326, 502, 610, 614 are physically isolated from eachother such that the fluid in each loop is isolated from the fluid in theremaining loops. For example, the engine coolant does not physicallycontact the exhaust coolant the heated coolant the organic generatorfluid of the ORC turbine-generator device 136 or the organic generatorfluid of the exhaust ORC turbine-generator device 318, etc. In thisregard, suitable piping, tubing, or other suitable conduit may be usedto route the flow of fluids described in greater detail herein.

The control unit(s) can divert generated power to the facility, to thepower grid and/or to a heating element 302 located inside the hotreservoir 128. Thus if there is no demand for electricity the recoveredwaste energy is stored as heat energy within the hot reservoir 128.Later, upon demand the ORC turbine-generator device 136 is commanded togenerate power using warm coolant pumped from the hot reservoir 128. Theother regenerative and bypass functionality are also maintained in thisembodiment.

According to aspects of the present disclosure, engine test cellsprovide improved performance and reliability, enhanced capabilities,better timing, and lower acquisition and operating costs. For instance,a closed system is provided, where a closed circuit conditioned fluidsupply does not allow cooling fluid to come in contact with theatmosphere, thus reducing the potential for contamination with less needfor additional make-up fluid. Further, automated quality monitoring andconditioning systems can be utilized to filter and adjust the recycledcooling fluid to maintain proper pH level, physical chemistry andlubricity. In this manner, there is no need for toxic chemicals orreagents.

Computer-based dashboard and facility displays can be utilized tohighlight energy recapture and savings. Moreover, the test cells herein,may be implemented within the greater test facility without connectionto the external utility grid. Thus, energy savings can be fully realizedwithout having to comply with any restrictions imposed by local utilityauthorities.

In the course of internal combustion engine product development orinternal combustion engine manufacturing, repair and/or overhauloperations, engines must be tested to ensure proper function andperformance. Internal combustion engine testing can generate largeamounts of waste energy. This waste energy is typically dissipated intothe atmosphere or other thermal reservoirs such as rivers, lakes orgeothermal wells. In addition to creating waste energy, internalcombustion engine testing systems often times require the input ofsubstantial additional energy from the utility grid to power pumps,fans, cooling systems, and other facility equipment. Also, the nature ofan engine testing facility, especially one that tests large engines orhas many test cells, can produce relatively large bursts of power whenthere may not be a demand for the energy within the local facility.Moreover, utility authorities are not always receptive to or capable ofreceiving these bursts of intermittent power onto the local grid,especially if an instantaneous demand does not exist. However, thesystems herein avoid these issues by capturing and optionally storingwaste energy for conversion to usable energy on demand concurrent withtesting or at a later time.

Moreover, the “quality” of the waste energy available from conventionalinternal combustion engine testing strategies may be consideredlow-grade waste heat. As such, most internal combustion engine testingfacilities opt to simply dissipate waste energy to the environment as a“cost of doing business”. However, according to aspects of the presentdisclosure, waste energy recapture methods allow waste energy to beconverted into useful energy, e.g., power on demand, even where wasteenergy is “low quality”. The generated electricity can defray the costof testing and satisfy other environmental and economic requirements.

Also, in some applications, the methods described herein can earnso-called “carbon credits” having direct or indirect monetary value forconverting waste energy to useful forms of energy that would haveotherwise resulted in greenhouse gases being released into theatmosphere without generating useful work.

Moreover, the systems herein can eliminate or reduce the additionalinput energy to power the testing facilities. Perhaps the most usefulform of converted waste energy is electricity, which is ubiquitous andcan be readily used by a multitude of applications, including using thegenerated electricity to power the testing system itself, powering otherfeatures of the test facility, combinations thereof, etc.

Flowchart and block diagrams in the Figures illustrate the architecture,functionality, and operation of possible implementations of systems andmethods according to various embodiments of the present disclosure. Insome implementations, the functions noted in the block may occur out ofthe order noted in the figures. For example, two blocks shown insuccession may, in fact, be executed substantially concurrently, or theblocks may sometimes be executed in the reverse order, depending uponthe functionality involved.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosureherein. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription herein has been presented for purposes of illustration anddescription, but is not intended to be exhaustive or limited to the formdisclosed. Many modifications and variations will be apparent to thoseof ordinary skill in the art without departing from the scope and spiritof the disclosure. Aspects of the disclosure were chosen and describedin order to best explain the principles of operation and the practicalapplication, and to enable others of ordinary skill in the art tounderstand the various embodiments with various modifications as aresuited to the particular use contemplated.

What is claimed is:
 1. An engine testing system, comprising: a coldreservoir; a rotary absorber; a hot reservoir; an Organic Rankine Cycle(ORC) turbine-generator device; a heated-fluid bleed pump coupledbetween the hot reservoir and the ORC turbine-generator device to supplyheated coolant from the hot reservoir to the ORC turbine-generatordevice; a control unit that determines an electrical load coupled to theORC turbine-generator device and instructs the heated-fluid bleed pumpto supply heated coolant to the ORC turbine-generator device based onthe electrical load coupled to the ORC turbine-generator device; aconditioning system; and a primary coolant loop arranged to enablecoolant to flow: from the cold reservoir to the rotary absorber, fromthe rotary absorber to the hot reservoir, from the hot reservoir to theORC turbine-generator device, from the ORC turbine-generator device tothe conditioning system, and from the conditioning system back to thecold reservoir; wherein: the rotary absorber provides a variableresistance to rotation of a shaft of an engine under test during anintermittent engine testing operation, producing waste energy; coolcoolant from the cold reservoir carries away the waste energy from therotary absorber as heated coolant, which is provided to the hotreservoir; the heated coolant from the hot reservoir is provided to theORC turbine-generator device, which converts heat from heated coolantinto electrical power; and the conditioning system conditions coolantfrom the ORC turbine-generator device for storage back in the coldreservoir.
 2. The engine testing system of claim 1 further comprising: aheating element that heats the coolant stored in the hot reservoir; anelectrical switch; a first circuit that electrically couples theelectrical switch to the heating element; and a second circuit thatelectrically couples the electrical switch to a device.
 3. The enginetesting system of claim 2 further comprising: a circuit from anelectrical output of the ORC turbine-generator device to the electricalswitch such that the ORC turbine-generator device can provide electricalpower to the first circuit, the second circuit, or both, depending upona state of the electrical switch.
 4. The engine testing system of claim2 further comprising: a turbine-generator that generates electricalpower using a flow of exhaust gases from the engine while the engine isrunning; and a circuit from an electrical output of theturbine-generator to the electrical switch.
 5. The engine testing systemof claim 2 further comprising: a heat exchanger that transfers wasteenergy in the form of heated exhaust from the engine under test to heatthat is carried away by an exhaust coolant; an exhaust turbine-generatordevice that converts heat from heated exhaust coolant into electricalpower; and a circuit from an electrical output of the exhaustturbine-generator to the electrical switch.
 6. The engine testing systemof claim 2 further comprising: an engine heat exchanger that transferswaste energy in the form of engine heat to an engine coolant thatcarries away heat from the engine under test; and a separate engineturbine-generator that converts heat from heated engine coolant intoelectrical power.
 7. The engine testing system of claim 1 furthercomprising: a heating element that heats the coolant stored in the hotreservoir; an electrical switch having a first circuit that iselectrically coupled to the heating element and a second circuit thatroutes power to an external device; a turbine-generator that generateselectrical power using a flow of exhaust gases from the engine while theengine is running and a circuit from an electrical output of theturbine-generator to the electrical switch; an exhaust coolant loopcomprising: a heat exchanger that transfers waste energy in the form ofheated exhaust from the engine under test to heat that is carried awayby an exhaust coolant; an exhaust turbine-generator device that convertsheat from heated exhaust coolant into electrical power; a secondaryexhaust coolant heat exchanger that cools the exhaust coolant when theexhaust turbine-generator is bypassed for return of the exhaust coolantto the heat exchanger; and a circuit from an electrical output of theexhaust turbine-generator to the electrical switch; and an enginecoolant loop comprising: an engine heat exchanger that transfers wasteenergy in the form of engine heat to an engine coolant that carries awayheat from the engine under test; an engine ORC turbine-generator devicethat converts heat from heated engine coolant into electrical power; anda circuit from an electrical output of the engine ORC turbine-generatorto the electrical switch.
 8. The engine testing system of claim 7,wherein: the exhaust turbine-generator comprises an ORCturbine-generator device.
 9. The engine testing system of claim 1,wherein the rotary absorber comprises: an electric generating devicethat converts the shaft power from the rotation of the shaft of theengine under test to electricity; and an electrical load applied to anoutput of the electrical generator device in order to produceresistance.
 10. The engine testing system of claim 1, wherein the ORCturbine-generator device comprises: a liquid heat exchanger that expandsa condensed organic generator fluid based on heat from the heatedcoolant to create expanded organic generator fluid; a turbine having ashaft that rotates in response to the expanded organic generator fluidentering the turbine; a generator coupled to the shaft of the turbinethat generates electrical power in response to rotation of the shaft; acondenser that condenses the expanded organic generator fluid to createthe condensed organic generator fluid; and a regenerator that reclaimsheat before the organic generator fluid is condensed by the condenser.11. The engine testing system of claim 1, wherein the conditioningsystem is configured to perform at least one of: treat the coolant tomaintain proper pH level and chemistry of the coolant; treat the coolantto maintain lubricity of the coolant; filter the coolant to removeimpurities; and further cool the coolant.
 12. The engine testing systemof claim 1, wherein the hot reservoir is an insulated reservoir.
 13. Theengine testing system of claim 1, wherein the hot reservoir is anelevated height reservoir.
 14. The engine testing system of claim 1further including a bypass valve that selectively directs the heatedcoolant to the ORC turbine-generator device in a first position anddirects coolant to the conditioning system in a second position.
 15. Theengine testing system of claim 1 further comprising: an engine heatexchanger that transfers waste energy in the form of engine heat to anengine coolant that carries away heat from the engine under test; and asecondary heat exchanger in the ORC turbine-generator device, such thatheat drawn by the ORC turbine-generator device for conversion toelectricity is from a combination of heat from the engine coolant andheat from the coolant from the hot reservoir.
 16. An engine testingsystem, comprising: a cold reservoir; a rotary absorber; a cool-coolantpump coupled between the cold reservoir and the rotary absorber tosupply cool coolant from the cold reservoir to the rotary absorber; ahot reservoir; a heated-fluid supply pump coupled between the rotaryabsorber and the hot reservoir to supply the heated coolant from therotary absorber to the hot reservoir; an Organic Rankine Cycle (ORC)turbine-generator device; a heated-fluid bleed pump coupled between thehot reservoir and the ORC turbine-generator device to supply the heatedcoolant from the hot reservoir to the ORC turbine-generator device; aconditioning system; a cool-fluid fill pump coupled between theconditioning system and the cold reservoir to fill the cold reservoirwith the coolant from the conditioning system; and a primary coolantloop arranged to enable coolant to flow: from the cold reservoir to therotary absorber, from the rotary absorber to the hot reservoir, from thehot reservoir to the ORC turbine-generator device, from the ORCturbine-generator device to the conditioning system, and from theconditioning system back to the cold reservoir; wherein: the rotaryabsorber provides a variable resistance to rotation of a shaft of anengine under test during an intermittent engine testing operation,producing waste energy; cool coolant from the cold reservoir carriesaway the waste energy from the rotary absorber as heated coolant, whichis provided to the hot reservoir; the heated coolant from the hotreservoir is provided to the ORC turbine-generator device, whichconverts heat from heated coolant into electrical power; and theconditioning system conditions coolant from the ORC turbine-generatordevice for storage back in the cold reservoir.
 17. The engine testingsystem of claim 16 further comprising: a heating element that heats thecoolant stored in the hot reservoir; an electrical switch; a firstcircuit that electrically couples the electrical switch to the heatingelement; and a second circuit that electrically couples the electricalswitch to a device.
 18. The engine testing system of claim 17 furthercomprising: a circuit from an electrical output of the ORCturbine-generator device to the electrical switch such that the ORCturbine-generator device can provide electrical power to the firstcircuit, the second circuit, or both, depending upon a state of theelectrical switch.
 19. The engine testing system of claim 17 furthercomprising: a turbine-generator that generates electrical power using aflow of exhaust gases from the engine while the engine is running; and acircuit from an electrical output of the turbine-generator to theelectrical switch.
 20. The engine testing system of claim 17 furthercomprising: a heat exchanger that transfers waste energy in the form ofheated exhaust from the engine under test to heat that is carried awayby an exhaust coolant; an exhaust turbine-generator device that convertsheat from heated exhaust coolant into electrical power; and a circuitfrom an electrical output of the exhaust turbine-generator to theelectrical switch.
 21. The engine testing system of claim 17 furthercomprising: an engine heat exchanger that transfers waste energy in theform of engine heat to an engine coolant that carries away heat from theengine under test; and a separate engine turbine-generator that convertsheat from heated engine coolant into electrical power.
 22. The enginetesting system of claim 16 further comprising: an engine heat exchangerthat transfers waste energy in the form of engine heat to an enginecoolant that carries away heat from the engine under test; and asecondary heat exchanger in the ORC turbine-generator device, such thatheat drawn by the ORC turbine-generator device for conversion toelectricity is from a combination of heat from the engine coolant andheat from the coolant from the hot reservoir.
 23. The engine testingsystem of claim 16 further comprising: a heating element that heats thecoolant stored in the hot reservoir; an electrical switch having a firstcircuit that is electrically coupled to the heating element and a secondcircuit that routes power to an external device; a turbine-generatorthat generates electrical power using a flow of exhaust gases from theengine while the engine is running and a circuit from an electricaloutput of the turbine-generator to the electrical switch; an exhaustcoolant loop comprising: a heat exchanger that transfers waste energy inthe form of heated exhaust from the engine under test to heat that iscarried away by an exhaust coolant; an exhaust turbine-generator devicethat converts heat from heated exhaust coolant into electrical power; asecondary exhaust coolant heat exchanger that cools the exhaust coolantwhen the exhaust turbine-generator is bypassed for return of the exhaustcoolant to the heat exchanger; and a circuit from an electrical outputof the exhaust turbine-generator to the electrical switch; and an enginecoolant loop comprising: an engine heat exchanger that transfers wasteenergy in the form of engine heat to an engine coolant that carries awayheat from the engine under test; an engine ORC turbine-generator devicethat converts heat from heated engine coolant into electrical power; anda circuit from an electrical output of the engine ORC turbine-generatorto the electrical switch.
 24. The engine testing system of claim 23,wherein: the exhaust turbine-generator comprises an ORCturbine-generator device.
 25. The engine testing system of claim 16,wherein the rotary absorber comprises: an electric generating devicethat converts the shaft power from the rotation of the shaft of theengine under test to electricity; and an electrical load applied to anoutput of the electrical generator device in order to produceresistance.
 26. The engine testing system of claim 16, wherein the ORCturbine-generator device comprises: a liquid heat exchanger that expandsa condensed organic generator fluid based on heat from the heatedcoolant to create expanded organic generator fluid; a turbine having ashaft that rotates in response to the expanded organic generator fluidentering the turbine; a generator coupled to the shaft of the turbinethat generates electrical power in response to rotation of the shaft; acondenser that condenses the expanded organic generator fluid to createthe condensed organic generator fluid; and a regenerator that reclaimsheat before the organic generator fluid is condensed by the condenser.27. The engine testing system of claim 16, wherein the conditioningsystem is configured to perform at least one of: treat the coolant tomaintain proper pH level and chemistry of the coolant; treat the coolantto maintain lubricity of the coolant; filter the coolant to removeimpurities; and further cool the coolant.
 28. The engine testing systemof claim 16, wherein the hot reservoir is an insulated reservoir. 29.The engine testing system of claim 16, wherein the hot reservoir is anelevated reservoir.
 30. The engine testing system of claim 16 furtherincluding a bypass valve that selectively directs the heated coolant tothe ORC turbine-generator device in a first position and directs coolantto the conditioning system in a second position.